Gradient-structured 1060 aluminum by air pressure-driven surface mechanical rolling treatment and its effects on the friction performance

Surface mechanical rolling treatment (SMRT) is well documented as a novel and promising surface selfnanocrystallization technology. An experiment platform of air pressure-driven surface mechanical rolling treatment was established innovatively, and the gradient-structured 1060 aluminum rod samples were accordingly fabricated by air pressure-driven SMRT. The air pressure, rolling pass and rotation speed of rod sample are the three parameters used for controlling the SMRT process. A three-factor and five-level orthogonal experiment table was designed to study the effects of the process parameters on the results of air pressure-driven SMRT of 1060 aluminum rod samples in terms of the surface roughness and in-depth microhardness. The experimental results show that the different combination of the three process parameters could obtain almost the same surface roughness or in-depth microhardness. Both the surface roughness and in-depth microhardness induced by air pressure-driven SMRT of 1060 aluminum rod samples are relatively more sensitive to the air pressure. Based on the microstructure observations, the grain refinement mechanism of 1060 aluminum induced by air pressuredriven SMRT was discussed in detail. The friction and wear experiments were further conducted to investigate the influences of the surface roughness and in-depth microhardness on the dry sliding wear behavior of the air pressure-driven SMRTed 1060 aluminum rod samples. In comparison to the reduction of surface roughness, the increase of the in-depth mircohardness has the more significant impact on the dry sliding wear behavior of the SMRTed 1060 aluminum rod samples.